Large liquid oxygen and liquefied natural gas production process

ABSTRACT

A process for co-producing a liquid oxygen and a liquefied hydrocarbon stream, including introducing a gaseous hydrocarbon stream and a gaseous nitrogen stream into a liquefier, thereby producing a liquefied hydrocarbon stream and a liquid nitrogen stream, liquefying a gaseous oxygen stream, wherein at least a portion of the required refrigeration is obtained from the liquid nitrogen stream. Wherein the liquefied hydrocarbon stream and the liquefied gaseous oxygen stream have mass flow rates. The liquid oxygen stream may be produced in an aft separation unit, wherein at least a portion of the required refrigeration is obtained from the liquid nitrogen stream.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to U.S. Provisional Patent Application No. 63/058,898, filed Jul. 30, 2020, the entire contents of which are incorporated herein by reference.

BACKGROUND

There is demand for large quantities of low-cost liquid oxygen (LOX) and liquefied natural gas (LNG) as rocket fuel for both the current and the emerging space industry. Oxygen and purified natural gas are both used due to their different fuel properties to provide different thrust, etc. in different specific stages of the rocket and their liquid forms are used due to higher densities for storage on the rocket. The resulting requirement for staging of one such demand is in the range of LOX/LNG mass flow ratio of between 3 and 4.

There are several methods are known for production of LOX and LNG in the art. First, these two streams are typically produced separately and independently liquefied. As an example, an air separation unit (ASU) produces pressurized gaseous oxygen (GOX) and a nitrogen liquefier cycle produces liquefied nitrogen (LIN) which is vaporized by indirect heat exchanges with natural gas (NG) and liquid oxygen (LOX) in independent systems yielding LOX and liquefied natural gas (LNG). This method is intensive in terms of both operating expense (OPEX) and capital expense (CAPEX) due to energy and heat exchanges needed to pressurize O2 and liquefy and re-vaporize LIN.

Alternatively the LNG can be independently liquefied yielding an efficient OPEX of approximately 0.28 kQ/Nm3 for LNG. However, this has a very high CAPEX due to the need of a separate and independent refrigeration cycle which may be mixed refrigerant, N2 expansion.

Another known method is to produce the LOX directly from the ASU with refrigeration provided by LIN from a N2 cycle liquefier to the ASU. This yields more efficient OPEX of approximately 0.51 kW/Nm3 for LIN as it removes the gaseous O2 compression step and indirect heat transfer between vaporizing LIN to condensing LOX. However, this does not solve the CAPEX penalties of requiring a separate independent LNG plant.

SUMMARY

A process for co-producing a liquid oxygen and a liquefied hydrocarbon stream, including introducing a gaseous hydrocarbon stream and a gaseous nitrogen stream into a liquefier, thereby producing a liquefied hydrocarbon stream and a liquid nitrogen stream, liquefying a gaseous oxygen stream, wherein at least a portion of the required refrigeration is obtained from the liquid nitrogen stream. Wherein the liquefied hydrocarbon stream and the liquefied gaseous oxygen stream have mass flow rates.

A process for co-producing a liquid oxygen and a liquefied hydrocarbon stream, including introducing a gaseous hydrocarbon stream and a gaseous nitrogen stream in a liquefier, thereby producing a liquefied hydrocarbon stream and a liquid nitrogen stream, producing a liquid oxygen stream in an air separation unit, wherein at least a portion of a required refrigeration is obtained from the liquid nitrogen stream. Wherein the liquefied hydrocarbon stream, the liquid nitrogen stream, and the liquid oxygen stream have mass flow rates.

BRIEF DESCRIPTION OF THE FIGURES

For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

FIG. 1 is a schematic representation of a non-limiting example of a combined ASU and LNG system as known to the art.

FIG. 2 is a schematic representation of a non-limiting example of a basic air separation system as known to the art.

FIG. 3 is a schematic representation of non-limiting example of liquefaction heat exchanger as known in the art.

FIG. 4 is a schematic representation of an air separation system in accordance with one embodiment of the present invention.

FIG. 5 is a schematic representation of a combined ASU and LNG system in accordance with one embodiment of the present invention.

ELEMENT NUMBERS

101=Inlet air stream

102=main air compressor (MAC)

103=compressed inlet air stream

104=front end purification

105=purified air stream

106=air separation unit (ASU)

107=low-pressure nitrogen stream

108=medium-pressure nitrogen stream

109=liquid oxygen stream

110=liquid oxygen storage

111=nitrogen liquefaction heat exchanger

112=liquid nitrogen stream

113=export liquid nitrogen stream

114=heat exchange

115=gaseous nitrogen stream

116=internal liquid nitrogen stream

117=inlet natural gas stream

118=liquid natural gas stream

119=liquid natural gas storage device

201=inlet air stream

202=main air compressor (MAC)

203=compressed inlet air stream

204=front end purification unit

205=purified inlet air stream

206=main heat exchanger

207=cold air stream

208=medium-pressure distillation column

209=oxygen-rich liquid stream

210=nitrogen reflux stream

211=low-pressure distillation column

212=cold waste nitrogen stream

213=low-pressure pure nitrogen stream

214=liquid oxygen stream

215=medium-pressure nitrogen stream

216=warm medium-pressure nitrogen stream

217=combined nitrogen reflux stream

350=warm mixed refrigerant return steam

351=mixed refrigerant compressor

352=pressurized mixed refrigerant stream

353=mixed refrigerant cooler

354=cooled pressurized mixed refrigerant stream

355=first pressure reducing vessel

356=first vapor portion

357=first liquid portion

358=first combined mixed refrigerant stream

359=intermediate mixed refrigerant stream

363=intermediate mixed refrigerant stream

364=LP nitrogen compressor

365=warm medium-pressure nitrogen stream

366=first nitrogen cooler

367=cooled medium-pressure nitrogen stream

368=combined medium-pressure nitrogen stream

369=MP nitrogen compressor

370=warm intermediate-pressure nitrogen stream

371=second nitrogen cooler

372=cooled intermediate-pressure nitrogen stream

373=HP nitrogen compressor

374=medium-pressure nitrogen stream

375=first nitrogen refrigeration stream

376=nitrogen expander

377=expanded nitrogen stream

378=second nitrogen refrigeration stream

379=third pressure reducing vessel

380=nitrogen vapor portion

381=nitrogen liquid portion

382=combined nitrogen stream

383=cold nitrogen recycle stream

384=second nitrogen recycle stream

385=first nitrogen recycle stream

386=mixed refrigerant pressure letdown valve

387=nitrogen refrigeration cycle pressure letdown valve

390=mixed refrigerant cycle

391=nitrogen refrigeration cycle

401=first portion of purified inlet air stream

402=second portion of purified inlet air stream

403=booster air compressor

404=boosted inlet air stream

405=first portion of boosted inlet air stream

406=second portion of boosted inlet air stream

407=cold boosted air stream

408=expander

409=expanded second portion of boosted inlet air stream

410=cold expanded second portion of boosted inlet air stream

411=combined nitrogen reflux stream

506=air separation unit (ASU)

510=liquid oxygen storage

511=liquefaction heat exchanger

516=liquid nitrogen stream

517=internal liquid nitrogen stream

518=export liquid nitrogen stream

519=inlet natural gas stream

520=liquid natural gas stream

521=liquid natural gas storage device

DESCRIPTION OF PREFERRED EMBODIMENTS

Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The following abbreviations are used herein; mixed refrigerant (MR), air separation unit (ASU), main air compressor (MAC), booster air compressor (BAC), liquefied natural gas (LNG), gaseous oxygen (GOX), liquid oxygen (LOX), liquid nitrogen (LIN), and liquid argon (LAR).

Turning now to FIG. 1, a non-limiting example of a combined ASU and LNG system as known to the art is described. Inlet air stream 101 is compressed in main air compressor (MAC) 102, thereby producing compressed inlet air stream 103. Compressed inlet air stream 103 is then introduced into front end purification device 104, thereby producing purified air stream 105. Purified air stream 105 then enters air separation unit 106. Air separation unit 106 produces at least low-pressure nitrogen stream 107, medium-pressure nitrogen stream 108, and liquid oxygen stream 109. Liquid oxygen stream 109 is sent liquid oxygen storage device 110. In order to produce the desired flowrate in liquid oxygen stream 109, it is necessary to introduce additional refrigeration duty into the ASU, in the form of internal liquid nitrogen stream 116.

Low-pressure nitrogen stream 107 and medium-pressure nitrogen stream 108 are introduced into nitrogen liquefaction heat exchanger 111. Nitrogen liquefaction heat exchanger 111 outputs at least at liquid nitrogen stream 112. Liquid nitrogen stream 112 is divided into export liquid nitrogen stream 113, and internal liquid nitrogen stream 116. Export liquid nitrogen stream 113 exchanges heat with inlet natural gas stream 117 in heat exchanger 114, thereby producing gaseous nitrogen stream 115 and liquid natural gas stream 118. Liquid natural gas stream 118 is sent to liquid natural gas storage device 119.

Turning now to FIG. 2, a non-limiting example of a basic air separation system as known to the art is described. Inlet air stream 201 is compressed in main air compressor (MAC) 202, thereby producing compressed inlet air stream 203. Compressed inlet air stream 203 is then introduced into front end purification device 204, thereby producing purified inlet air stream 205. Purified inlet air stream 205 then enters main heat exchanger 206. Inside main heat exchanger 206, purified inlet air stream 205 indirectly exchanges heat with at least warm waste nitrogen stream 212 (below), and medium-pressure nitrogen stream 215 (below). This indirect heat exchange thus produces cold air stream 207, which is introduced into medium-pressure distillation column 208.

Medium-pressure distillation column 208 produces at least oxygen-rich liquid stream 209 and nitrogen reflux stream 210. Nitrogen reflux stream 210 is combined with internal liquid nitrogen stream 116 from liquefaction heat exchanger 111 to form combined nitrogen reflux stream 217. Oxygen-rich liquid stream 209 and combined nitrogen reflux stream 2171 are then both introduced into low-pressure distillation column 211.

Low-pressure distillation column 211 produces at least cold waste nitrogen stream 212, and liquid oxygen stream 214. Medium-pressure distillation column 208 also produces medium-pressure nitrogen stream 215. Medium-pressure nitrogen stream 215 is introduced into main heat exchanger 206 and exits as warm medium-pressure nitrogen stream 216. Cold waste nitrogen stream 212 is introduced into main heat exchanger 206 and exits as low-pressure pure nitrogen stream 213

Turning now to FIG. 3 details of one non-limiting example of liquefaction heat exchanger 511 (as described below) as known in the art are illustrated. In the interest of clarity and consistency, element numbers 507 (low-pressure nitrogen stream), 508 (medium-pressure nitrogen stream), 516 (liquid nitrogen stream), 519 (inlet natural gas stream), and 520 (liquid natural gas stream) from FIG. 5 are used.

Mixed refrigerant cycle 390 includes warm mixed refrigerant return steam 350, which is at reduced pressure. Mixed refrigerant return stream 350 has the pressure increased in mixed refrigerant compressor 351, thereby producing pressurized mixed refrigerant stream 352. Pressurized mixed refrigerant stream 352 enters mixed refrigerant cooler 353, thereby producing cooled pressurized mixed refrigerant stream 354. Cooled pressurized mixed refrigerant stream 354 is introduced to first phase separator vessel 355, which produces first vapor portion 356 and first liquid portion 357. First vapor portion 356 and first liquid portion 357 may be combined to form first combined mixed refrigerant stream 358, which is introduced into liquefaction heat exchanger 511. Alternatively, first liquid portion 357 and first vapor portion 356 may be introduced independently to exchanger 511 and first vapor portion 356 is cooled to a colder temperature than first liquid portion 357 (not shown). In general, it is understood that there are numerous variations of the mixed refrigerant system which one of ordinary skill in the art knows to apply in similar cycles.

After passing through liquefaction heat exchanger 511, first combined mixed refrigerant stream 358 exits as intermediate mixed refrigerant stream 359. Intermediate mixed refrigerant stream 359 is reduced in pressure across mixed refrigerant pressure letdown valve 386 and then is introduced into liquefaction heat exchanger 511 as intermediate mixed refrigerant stream 363. After passing through liquefaction heat exchanger 511, intermediate mixed refrigerant stream 363 exits as warm mixed refrigerant return steam 350.

Nitrogen refrigeration cycle 391 includes receiving low-pressure nitrogen stream 507 from the air separation unit 506 (not shown in FIG. 3). Low-pressure nitrogen stream 507 is combined with first nitrogen recycle stream 385, and the pressure of the combined stream is increased in LP nitrogen compressor 364, thereby producing warm medium-pressure nitrogen stream 365. Warm medium-pressure nitrogen stream 365 enters first nitrogen cooler 366, thereby producing cooled medium-pressure nitrogen stream 367.

Cooled medium-pressure nitrogen stream 367 is combined with medium-pressure nitrogen stream 508 from the ASU and second nitrogen recycle stream 384, thereby producing combined medium-pressure nitrogen stream 368. The pressure of medium-pressure nitrogen stream 368 is increased in MP nitrogen compressor 369, thereby producing warm intermediate-pressure nitrogen stream 370. Warm intermediate-pressure nitrogen stream 370 enters second nitrogen cooler 371, thereby producing cooled intermediate-pressure nitrogen stream 372.

Cooled intermediate-pressure nitrogen stream 372 is then further compressed in HP nitrogen compressor 373, thereby producing medium-pressure nitrogen stream 374. Medium-pressure nitrogen stream 374 then passes through liquefaction heat exchanger 511, after which it is removed at two locations. Typically, first nitrogen refrigeration stream 375 will be removed as a vapor stream, and second nitrogen refrigeration stream 378 will be removed as a liquid stream.

The first location is via first nitrogen refrigeration stream 375, which is then introduced into nitrogen expander 376. Nitrogen expander 376 is connected to HP nitrogen booster 373 by a common drive shaft. After having the pressure reduced in nitrogen expander 376, this stream exits as expanded nitrogen stream 377, which is then introduced into liquefaction heat exchanger 511. Expanded nitrogen stream 377 exits liquefaction heat exchanger 511 as second nitrogen recycle stream 384.

The second location is via second nitrogen refrigeration stream 378. Second nitrogen refrigeration stream 378 passes through nitrogen refrigeration cycle pressure letdown valve 387 and is then introduced into third phase separator vessel 379. This produces nitrogen vapor portion 380 and nitrogen liquid portion 381. Nitrogen vapor portion 380 and nitrogen liquid portion 381 are combined to form combined nitrogen stream 382. A portion of combined nitrogen stream 382 is removed as liquid nitrogen stream 516. The remaining portion of combined nitrogen stream 382 is introduced into liquefaction heat exchanger 511 as cold nitrogen recycle stream 383. Cold nitrogen recycle stream 383 exits liquefaction heat exchanger 511 as first nitrogen recycle stream 385. Mixed refrigerant cycle 390 and nitrogen refrigeration cycle 391 work together to provide sufficient refrigeration duty to liquefy inlet natural gas stream 519 into liquid natural gas stream 520. In addition, these combined refrigeration streams also provide sufficient additional refrigeration duty via internal liquid nitrogen stream 517, to satisfy the duty requirements of air separation unit 506 (not shown in FIG. 3). A portion 518 of liquid nitrogen stream 516 may be removed as LIN product (i.e. not sent to ASU).

Turning now to FIG. 4, an example of an air separation system in accordance with the present invention is described. In the interest of clarity and consistency, element numbers that are common with FIG. 2 are maintained.

Inlet air stream 201 is compressed in main air compressor (MAC) 202, thereby producing compressed inlet air stream 203. Compressed inlet air stream 203 is then introduced into front end purification device 204, thereby producing purified inlet air stream 205. Purified inlet air stream 205 is divided into at least a first portion 401 and a second portion 402. First portion 401 of purified inlet air stream then enters main heat exchanger 206. Inside main heat exchanger 206, first portion 401 of purified inlet air stream indirectly exchanges heat with a number of streams (described below) thus producing cold air stream 207. Cold air stream 207 is then introduced into medium-pressure distillation column 208.

Second portion 402 of purified inlet air stream has the pressure increased in booster air compressor 403, which produces boosted inlet air stream 404. Boosted inlet air stream 404 is divided into at least a first portion 405 and a second portion 406. First portion 405 of boosted inlet air stream then enters main heat exchanger 206. Inside main heat exchanger 206, first portion 405 of boosted inlet air stream indirectly exchanges heat with a number of streams thus producing cold boosted air stream 407. Cold boosted air stream 407 is then introduced into medium-pressure distillation column 208.

Second portion 406 of boosted inlet air stream is then reduced in pressure in expander 408, which produces expanded second portion of boosted inlet air stream 409. Expanded second portion of boosted inlet air stream 409 then enters main heat exchanger 206. Inside main heat exchanger 206, expanded second portion of boosted inlet air stream 409 indirectly exchanges heat with a number of streams thus producing cold expanded second portion of boosted inlet air stream 410. Cold expanded second portion of boosted inlet air stream 410 is then introduced into medium-pressure distillation column 208.

Medium-pressure distillation column 208 produces at least oxygen-rich liquid stream 209 and nitrogen reflux stream 210. Nitrogen reflux stream 210 is combined with internal liquid nitrogen stream 517 from liquefaction heat exchanger 511 (below), to form combined nitrogen reflux stream 411. Oxygen-rich liquid stream 209 and combined nitrogen reflux stream 411 are then both introduced into low-pressure distillation column 211.

Low-pressure distillation column 211 produces at least cold waste nitrogen stream 212, and liquid oxygen stream 214. Medium-pressure distillation column 208 also produces medium-pressure nitrogen stream 215. Medium-pressure nitrogen stream 215 is introduced into main heat exchanger 206 and exits as warm medium-pressure nitrogen stream 216. Cold waste nitrogen stream 212 is introduced into main heat exchanger 206 and exits as low-pressure pure nitrogen stream 213

Turning now to FIG. 5, a combined ASU and LNG system according to one embodiment of the present invention is described. In the interest of clarity and consistency, element numbers that are common with FIGS. 2 and 4 are maintained.

Inlet air stream 201 is compressed in main air compressor (MAC) 202, thereby producing compressed inlet air stream 203. Compressed inlet air stream 203 is then introduced into front end purification device 204, thereby producing purified air stream 205. Purified air stream 205 is divided into first air stream 401 and second air stream 402. First air stream 401 enters ASU 506. Second air stream 402 is further compressed in booster air compressor (BAC) 403, thereby producing boosted air stream 404. Boosted air stream 404 then enter air separation unit 506.

Air separation unit 506 produces at least low-pressure pure nitrogen stream 213, warm medium-pressure nitrogen stream 216, and liquid oxygen stream 214. Liquid oxygen stream 214 is sent liquid oxygen storage device 510. In order to produce the desired flowrate in liquid oxygen stream 214, it is necessary to introduce additional refrigeration duty, in the form of internal liquid nitrogen stream 517.

Low-pressure pure nitrogen stream 213, warm medium-pressure nitrogen stream 216, and inlet natural gas stream 519 are introduced into liquefaction heat exchanger 511. Liquefaction heat exchanger 511 outputs at least liquid natural gas stream 520 and liquid nitrogen stream 516. A portion of liquid nitrogen stream 516 may be removed as export liquid nitrogen stream 518, and not sent to the ASU. Liquid natural gas stream 520 is then sent to liquid natural gas storage device 521.

The objective of the current system is to optimize, in terms of operating expense and capital expense, a process for production of LOX and LNG with a mass flow ratio of LOX/LNG between 2 to 5, preferably between 3 to 4. As used herein, the mass flow ratio of LOX/LNG is defined as the mass flowrate of liquid oxygen stream 509 divided by the mass flowrate of liquid natural gas stream 520.

Ordinarily, ASU process designs (and indeed standard ASUs) are designed and optimized around a system which utilizes a MAC and a BAC, or a single high-pressure MAC, to produce primarily medium-pressure gaseous oxygen GOX with small (or negligible) amounts of cryogenic liquid (such as LOX, LIN, and/or LAR). Typically, such a system produces the GOX at a pressure of between 40 and 50 bara.

However, one aspect of the current invention is to use all of the available compression energy to produce primarily (or exclusively) LOX. As described above, the prior art system indicated in FIG. 1 does not include a BAC. Such systems are indeed very common. However, the current invention includes a BAC, which adds additional refrigeration capability. In the present case, the system is designed such that this additional refrigeration is being optimized to produce LOX. This optimization and the increased refrigeration available within the ASU, thus allows for the overall required refrigeration duty of liquefaction heat exchanger 511 to be reduced.

Specifically, in order to provide additional refrigeration duty to a cycle, additional energy must be added to the cycle. In this case, the additional energy comes in the form of the energy required by BAC 403 to increase the pressure in boosted inlet air stream 404. Then, the basic principle of isentropic expansion, through expander 408, results in expanded second portion 409. Expanded second portion 409 will have essentially the same entropy as boosted inlet air stream 404, but since it will be at a significantly lower pressure, will be significantly colder, thus adding significant additional refrigeration duty to the cycle.

In the present inventive system, this increase in internal refrigeration duty provided by BAC 403 will add between 10% to 50%, preferably 20% to 40%, or at least 10%, of the total refrigeration duty to the ASU cycle to produce liquid products LOX and/or LIN with preferably no (or very small) gaseous products. This will reduce the refrigeration required by mixed refrigerant cycle 390 and/or nitrogen refrigeration cycle 391 accordingly.

In general, the specific power to produce LOX is about 3 times larger than the power to produce only medium-pressure GOX. Therefore, an optimized MAC/BAC (or single high-pressure MAC) ASU scheme is only able to provide approximately ⅓^(rd) of the refrigeration required to liquefy all of the LOX. The remainder of the required refrigeration (i.e, approximately ⅔rds) must be provided by external source (such as imported LIN).

A second aspect of the current invention is to incorporate a liquefier process which simultaneously produces the required balance (approximately ⅔^(rd) portion) of the LOX refrigeration demand. The liquefier is designed to produce approximate LIN/LNG mass flow ratio of between 2 to 5, (preferably 2.5 ) since the final product demand is LOX/LNG in the mass flow ratio of between 3 to 4 (preferably 3.4). A third aspect of this invention is an optimized (especially relating to operating expense and capital expense) process scheme for producing this LIN/LNG mass flow ratio of 2 to 5, preferably 2 to 3 (more preferably 2.5). As used herein, the mass flow ratio of LIN/LNG is defined as the mass flowrate of internal liquid nitrogen stream 517 divided by the mass flowrate of liquid natural gas stream 520.

Mixed refrigerant (MR) refrigeration cycles are state-of-art for producing LNG but are not cold enough (−160 C for MR cycle) to produce LIN (−190 C). State-of-art LIN production is with N2 cycle only since the capital expenditure penalty of having both N2+MR cycles is not compensated by the operating expense efficiency savings to produce only LIN. However, producing the target LIN/LNG mass flow ratio of 2.5 yields a significant MR refrigerant (−160 C level refrigeration) as compared to the N2 cycle (−190 C level refrigeration) which allows for an optimized heat exchange profile.

In other words, a target LIN/LNG=2.5 mass flow ratio yields an optimized split of the refrigeration load between N2 cycle and MR cycle where the MR cycle supplements the traditional N2 cycle to produce LIN. The result is taking state-of the art LNG specific power (0.27 kW/Nm3) and applying the balance of power to the LIN we find 0.41 kW/Nm3 LIN which is 20 to 25% less than N2 expansion only cycle.

EXAMPLE

The mass flowrate of liquid oxygen stream 509=4300 metric tons per day

The mass flowrate of liquid natural gas stream 520=1250 metric tons per day

The mass flowrate of internal liquid nitrogen stream 517=2000 metric tons per day

The mass flow ratio of LOX/LNG=4300/1250=3.4

The mass flow ratio of LIN/LNG=3192/2000=4.2

The mass flow ratio of LIN to ASU/LOX produced=3192/4300=0.74

It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above. 

What is claimed is:
 1. A process for co-producing a liquid oxygen and a liquefied hydrocarbon stream, comprising: introducing a gaseous hydrocarbon stream and a gaseous nitrogen stream into a liquefier, thereby producing a liquefied hydrocarbon stream and a liquid nitrogen stream, liquefying a gaseous oxygen stream, wherein at least a portion of he required refrigeration is obtained from the liquid nitrogen stream, wherein the liquefied hydrocarbon stream and the liquefied gaseous oxygen stream have mass flow rates.
 2. The process of claim 1, wherein the ratio of mass flow rates of the liquefied gaseous oxygen stream and the liquefied hydrocarbon stream is between 2 to
 5. 3. The process of claim 1, wherein the ratio of mass flow rates of the liquefied gaseous oxygen stream and the liquefied hydrocarbon stream is between 3 to
 4. 4. The process of claim 1, wherein the liquefier uses a dual refrigerant liquefaction process, comprising a first refrigerant and a secondary refrigerant.
 5. The process of claim 4, wherein the first refrigerant is nitrogen or neon or a mixture of neon and nitrogen.
 6. The process of claim 4, wherein the secondary refrigerant is a hydrocarbon mixed refrigerant.
 7. A process for co-producing a liquid oxygen and a liquefied hydrocarbon stream, comprising: introducing a gaseous hydrocarbon stream and a gaseous nitrogen stream in a liquefier, thereby producing a liquefied hydrocarbon stream and a liquid nitrogen stream, producing a liquid oxygen stream in an air separation unit, wherein at least a portion of a required refrigeration is obtained from the liquid nitrogen stream, wherein the liquefied hydrocarbon stream, the liquid nitrogen stream, and the liquid oxygen stream have mass flow rates.
 8. The process of claim
 7. wherein the ratio of mass flow rates of the liquid oxygen stream and the liquefied hydrocarbon stream is between 2 to
 5. 9. The process of claim 7, wherein the ratio of mass flow rates of the liquid oxygen stream and the liquefied hydrocarbon stream is between 3 to
 4. 10. The process of claim 7, wherein the ratio of mass flow rates the liquid nitrogen stream to the liquid oxygen stream is 0.5 to 1.1.
 11. The process of claim 7, wherein the liquefier uses a dual refrigerant liquefaction process, comprising a first refrigerant and a secondary refrigerant.
 12. The process of claim 11, wherein the first refrigerant is nitrogen or neon or a mixture of neon and nitrogen.
 13. The process of claim 11, wherein the secondary refrigerant is hydrocarbon mixed refrigerant.
 14. The process of claim
 7. wherein at least a portion of the refrigeration required to liquefy the oxygen is from an auxiliary refrigeration produced within the air separation unit.
 15. The process of claim 14, wherein the auxiliary refrigeration is produced within the air separation unit with a main air compressor and/or a booster air compressor.
 16. The process of claim 15, wherein the auxiliary refrigeration is produced from at least 10% of the combined main air compressor and/or booster air compressor energy.
 17. The process of claim
 7. where the pressurized gaseous oxygen and/or gaseous nitrogen stream are produced by pumping of liquid and vaporizing.
 18. The process of claim 7, wherein at least a portion of the liquid oxygen stream is subcooled by heat exchange in the air separation unit with a nitrogen stream.
 19. The process of claim 7, wherein the air separation unit produces both a liquid oxygen stream with a mass flowrate and a gaseous oxygen stream with a mass flowrate, the liquid oxygen stream mass flowrate is added to the gaseous oxygen stream mass flowrate to produce a total oxygen mass flowrate, and wherein at least 90% of the of the total oxygen mass flowrate is liquid oxygen. 